Manufacture of cyclic amidines



Patented Aug. 22, 1944 MANUFACTURE OF OYCLIC AMIDINES Paul Schlack,Berlin-Trenton. Germany: vested in the Allen Property Custodian NoDrawing. Application May 18, 1940, Serial No. 336,001. In GermanyFebruary 9, 1%!39 4 Claims.

This invention relates to the manufacture of cyclic amidines andartificial materials produced thereof.

It is an object of the present invention to produce reactivepolyfunctional amidine compounds.

A further object is the production of polyfunctional amidine compoundswhich may be transformed directly into synthetic materials.

These and other objects will be apparent'from the following description.

It has been found, that polyfunctional amidine compounds of wide. use,which are suitable for the synthesis of artificial materials and whichmay be worked up under certain conditions directly into such artificialmaterial, are obtained, if O-substituted enol compounds of lactams arecaused to react with polyfunctional compounds containing more than oneamino group or at least one amino group and at least one hydroxyl orsulfhydryl group of aliphatic character or at least one carboxyl groupor a transformed carboxyl group, e. g., a nitrile group, ester group oramide group, whereby, if necessary, either the lactam derivatives or thecounter components containing amino groups may be present in the form ofsalts. If a polyvalent amino compound functioning as counter componentis saturated with a polyvalent carboxylic acid, primary reactionproductsare obtained; which, if further heated at a correspondingly hightemperature of for instance I'm-270 0., turn into high molecularpolyamides.

The primary reactions with the lactam derivatives were found to run ofias a rule very smoothly, though side reactions on account of ring 7cleavage have to be taken into consideration at least with lactamshaving more than six ring members. For this process there may beemployed in principle oxygen derivatives, for instance O-alkyl ether orO-ester of all lactams.

For the synthesis of polyamide artificial materials, however, espeoiallythose products are valuable which are derived from lactams with at leastseven atoms in the ring. As starting material there may be mentioned thefollowing: the O-methylethers from 'y-butyrolactam, the O- nlethylethersfrom a-valerolactam, the O-methylethers from e-caprolactam, theO-methylethers of the C-methyL-e-caprolactams and the methylethers ofthe lactam of the {-amino heptylic acid (suberone isoxime), further the0-hbutylether and the O-phenylether'and the benzenesulfoester of theenolic' e-caprolactam.

The O-allwlethers areobtained in the usual manner by the reaction of thelactimsulfoester was found, by the reaction of the lactams with.

dialkylsulfates or arylsulfo acid esters, preferably in the presence ofindifierent solvents like benzene or xylene. Also the alkylsulfonic acidesters, as further was found, are reactive and may be used for thereactions either as such or transformed into the distillable lactimethers. The alkylsulfonic acid esters are obtainable, if alkyl sulfochlorides, for instance propanesulfo chloride or propane disulfochloride are caused to react with lactams in the presence of \tertiaryamines, for instance pyridine.

For the transformation of the lactam derivatives (lactimcompounds), intoamidines for in-' stance the following polyfunctional amino compoundsor, if the free lactimethers are used also their salts, for instancewith hydrochloric acid, toluen sulfonic acid, adiplc acid, sebacic acidmay be employed: Ethylenediamine, diethylenetriamine, polyethyleneimine,putrescin, hexamethylenediamine, symm. dimethylhexamethylenediamine,octamethylenediamine, pp'-diaminodiethylether.

Other suitable amino compounds are: 3.3,- diaminodipropylsulfide,3-aminopropandiol-1, 5- aminopentanol-l, 5-aminoamylmercaptan-1, 6-aminohexaneacid (sodium salt), fi-aminohexane acid nitrile,G-aminohexane acid methy'lester.

The change into amidine compounds may be accomplished already by usingthe primary reaction products produced for instance by the unificationof lactamand dimethylsulfate, if the formation of the lactim compoundsis brought This simplifies the procedure very much. Usually the reactionis carried out in aqueous, alcoholic or alcoholic-- aqueous solution. Insome cases, especially with very unstable cyclic compounds, the use ofwaterand hydroxyl-free solvents is preferred, e. g.,

tetrahydrofuran, dioxane, glycol formal, methylenechloride and benzene.Needless to say also the solubility of the reaction mixture and thecapability of being isolated is important for the selection of thesolvent. By the reaction of the free lactim ethers with amines, ifnecessary in the presence of a small portion of catalytically effectivehydrogen halide, the amidines are obtained immediately in the form ofthe free bases. If one starts from lactim ether'salts, thecor-responding amidine salts are obtained. The same applies to thepossible reaction of free lactim ethers with amine salts and thereaction of amine bases with sulfoesters of the'enolic lactams. Whenworking with delicate salts it is of advantage to use waterandhydroxyl-free solvents so that ring cleavage is avoided. In thisconnection it is important; to note that the addition compounds ofdiethylsulfates and arylsulfonic acid esters with many lactams aresoluble in hydrocarbons containing chlorine and in benzene. From thesesolutions. the free ethers may be obtained by discharging them intopotassium carbonate solution .and purifying them by distillation. Alsobya double-reaction with salts of other acids, e. g., of dlcarboxylicacids, valuable intermediate products adapted for artificial materialsmay be precipitated.

The products according to this invention are most useful as such or inthe form of their reaction products as auxiliary agents in the textileindustry and related branches of the chemical technology. They areespecially adapted as intermediate products for the productionofsynthetic resins or artificial materials. Such products were obtained,if the reaction product of the lactim compounds with at least two aminogroups or with amino groups and at least one hydroxyland sulfhydrylgroup are heated up with dior polycarboxylic acids or, if the products,still containing carboxyl groups besides the newly formed amidinegroups, are condensed with themselves'in the heat or finally, ifproducts showing still transformed carboxyl groups besides the amidinegroups, e. g. nltrile groups and carboxyl acid ester groups are heatedup at higher temperatures, for instance ISO-300 C.,

in the presence of water or compounds capable of splitting oiT water,forinstance condensable amino acids or salts of diamines anddicarboxylic acids. I

Instead of the free amidine compounds also salts of these compounds withvolatile acids like carbonates and especially formates, also productswith methylated amino groups may be used. If n'itrile compounds areused, one works according to my U. S. patent application Serial No.308,093,

filed December 7, 1939; for formyl compounds see my U. S. patentapplication Serial No.

307,984, filed December 7, 1939, now Patent No. 2,277, 152.

If bifunctional compounds according to this invention are condensed withdicarboxylic acids or derivatives of such acids, if necessary in thepresence of water, alcohol or compounds capable of splitting ofi water,especially also of products forming condensation polymers bydehydration, like w-amino acids, w-oxy acid or of mixtures of aboutequivalent portions of aw-diamines or aw-dicarboxylic acids and ifnecessary of reaction accelerating or regulating modifying agents, for

instance mineral acids or compounds splitting oil such acids, likehydrochloric acids, toluene sulfo acid, benzylchlo'ride or of saltsof-bases with strong acids like ammonium chloride, hydroe two mollactim, and if then the condensation is continued without purification,in the first case by adding a nearly equivalent portion of died);-

boxylic acid calculated by titration. The condensations may take placeat ordinary, increased or reduced pressure. It is often useful to carryout the first step under pressure, whereby the reaction may beconsiderably accelerated. The increase in pressure may be accomplishedby adding indifferent liquids of,low vapor-pressure, by adding water oralcohol, by alcohol formed during the reaction or by forcing in-anindifferent gas, for instance nitrogen.

If products containing more than two functional groups are used,three-dimensional more or less insoluble and iniuslble structures areobtained. Such products may be formed in the way of phenolplasts(condensation products of phenols and formaldehyde) or aminoplasts(condensation products of urea and/or thiourea with formaldehyde) byworking them in a low polymeric state and by a. subsequent hardeningprocess, if necessary mixed with filling materials. In most cases it ispreferable to work the products with more than two functional groupstogether with bifunctional ones in portions lonly, whereby the physicalproperties of the final products may be modified within wide limits.These compounds for instance may be condensed together with aldehydesand resin-forming amides like urea, thiourea, dicyandiamide andheterocyclic polyvalent amino compounds, for instance diand triaminotriazines. Polyfunctional amidines with at least two exchangeablehydrogen-on-nitrogen atoms may be condensed or pressed into resinsdirectly with compounds splitting off aldehyde likeformaldehyde,'p-formaldehyde, hexamethylenetetramine and the like.

Example I e-caprolactam is transformed in benzene solution (3 volumeparts benzene to 1 volume part lactam) by boiling for 6 hours with theequivalent amount of dimethylsulfate into the methylsulfuric acid saltof the lactim methyl ether, which is slightly soluble in benzene. Thebenzene solution, which does not contain a precipitate, i dischargedinto a 50 per cent potassium carbonate solution, which is in excess andcovered with a layer of ether, thus liberating the lactim ether. It isobtained by fractional distil lation of the dried benzene-ether layer ingood output as colorless, terpene-like smelling liquid (B. PA 50-52 C.).

Two mols lactim ether are dissolved in the same volume of alcohol andmixed with one mol hexamethylenediamine. After. standing over night itis heated some more hours on the water bath and then the alcohol isdistilled off. The

' turbing, volatile ingredients are practically not formed. I

-. Instead of the free amidines the dihydrochloride is obtained, if thehexamethylenediamine is 1 methylhexamethylenediamine.

Example II From the lactim ether of the e-caprolactam obtained accordingto Example I a product is obtained directly condensable into polyamideby heating at 200-260 C., if two mols lactim ether are mixed with onemol hexamethylenediamineadipic acid salt in hot alcoholic solution, themixture then heated for several hours at 100 0., the alcohol thendistilled oil and the condensation is carried through at 220-260 C.Finally also two mols of the lactim ether and one mol salt may begradually heated at 200-220" C. in a silver plated autoclave without asolvent, the pressure be relieved and the condensation be finished atExample 111 lactamis stirred while cooling into an alcoholic solutioncontaining an excess of hexamethylenediamine. The reaction productpresents a mix- The 5-aminohexanol of Example III is substituted by theequivalent amount of fi-aminoamylmercaptan. The mercaptoamidine iscondensed 'into a resin with formaldehyde in the presence of formic acidor oxalic acid.

I Example V The lactim methyl ether from e-caprolactam is left overnightwith the equimoiecular amount B-aminohexane acid nitrile in alcoholicsolution by adding ,4 mol hydrochloric acid to 1 mol lactim ether andthen (after 16 hours) heated on a steam bath for still a certain while.The reaction product remaining after the distillation is Example VI Thelactim methyl ether from 4-methylcyclohexanone-isoxime (mixture of 2stereoisomers) is condensed with the equimolecular amount diethylenetriamine. The reaction product gives a basic synthetic resin when heatedwith aqueous formaldehyde in the presence of acetic acid, which is usedas auxiliary agent for dyestuil' purposes.

Example VII The benzene sulfo ester of the enolic a-caproture, partlyneutralized by benzene sulfo acid, consisting of the symmetricalhexamethylenediamidine, hexamethylenediamine and a compound obtained byreaction of 1 mol hexamethylenediamine and 1 mol lactim ester. Themixture may be directly used for the production of artificial materialsby condensing with a dicarboxylic acid approximately corresponding tothe amount of'basic substances. The excess of hexamethylene diamine maybe removed from the mixture of the free bases by distillation. Thebenzene sulfo ester is obtained by a reaction of the lactam with thesulfo chloride while sufficiently cooling in the presence of a tertiarybase like pyridine.

- Example VIII 1 mol piperidon is transformed in the presence ofpyridine with propane sulfo chloride into the lactim sulfo ester. By thereaction of the ester with a solution of sodium butylate in n-butanolthere is obtained the lactim butyl ether'which is distiliable withoutdecomposition in the vacuum. By heating of the lactim ether with halfthe equivalent of water-free ethylenediamine at 140 C. a reactionproduct by' cleavage of butanol is obtained being condensable withformaldehyde sulfo esters with an aliphatic polyi'unctional r the classconsisting oi! water and alcohols.

3. Process according to claim 1 in which the polyfunctional compoundsare di-primary di amines.

4. Process according t'o'claim 1 in which the polyfunctional compoundsare salts consisting of amdiamines and au dicarboxylic acids.

RAUL soar-sex.

